Abstract
Floor panels which are provided with a mechanical locking system including a displaceable tongue in a displacement groove. The tongue is moulded and provided with bendable protrusions. A building panel having an edge portion provided with a groove, in which a tongue formed as a separate part is received, wherein the tongue includes at least two bow shaped protrusions at a first long edge of the tongue, and wherein the protrusions are arranged bendable in the groove.
Claims
1. A building panel having an edge portion provided with a groove, in which a tongue formed as a separate part is received, wherein the tongue comprises a tongue body and a protrusion at an edge of the tongue body, wherein the protrusion and the tongue body are spaced by a space between the protrusion and the tongue body, wherein the protrusion is bendable into the space, and in the groove, and wherein an outer part of the protrusion comprises a round shaped protruding part configured to facilitate installations with vertical folding, wherein the round shaped protruding part is round shaped in a width direction of the tongue, such that a width of the round shaped protruding part varies along a longitudinal direction of the tongue.
2. The building panel as claimed in claim 1, wherein the tongue comprises a polymer material.
3. The building panel as claimed in claim 2, wherein the polymer material is polyamide(nylon), polyoxymethylene, polycarbonate, polypropylene, polyethylene terephthalate, or polyethylene.
4. The building panel as claimed in claim 1, wherein the round shaped protruding part extends outside the groove.
5. A building panel as claimed in claim 1, wherein the tongue is of an elongated shape and made of moulded plastic.
6. A building panel having an edge portion provided with a groove, in which a tongue formed as a separate part is received, wherein the tongue comprises a tongue body and a protrusion at an edge of the tongue body, wherein the tongue body has a length in the longitudinal direction of the tongue, wherein the protrusion and the tongue body are spaced by a space between the protrusion and the tongue body, wherein the protrusion is bendable into the space, and in the groove, and wherein an outer part of the protrusion comprises a round shaped protruding part configured to facilitate installations with vertical folding, wherein a portion of the round shaped protruding part extends outside the groove, wherein a length of the portion of the round shaped protruding part extending outside of the groove is less than the length of the tongue body.
7. The building panel as claimed in claim 6, wherein the tongue comprises a polymer material.
8. The building panel as claimed in claim 7, wherein the polymer material is polyamide (nylon), polyoxymethylene, polycarbonate, polypropylene, polyethylene terephthalate, or polyethylene.
9. A building panel as claimed in claim 6, wherein the tongue is of an elongated shape and made of moulded plastic.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIGS. 1a-d illustrate a known art locking system.
(2) FIGS. 2a-b show a known art flexible tongue during the locking action.
(3) FIGS. 3a-b show a floor panels with a known art mechanical locking system on a short side.
(4) FIGS. 4a-b show how short sides of two floor panels could be locked with vertical folding according to known art.
(5) FIGS. 5a-c show panels according to one embodiment of the invention and a preferred locking method.
(6) FIGS. 6a-e show displaceable tongues in embodiments according to the invention.
(7) FIGS. 7a-b show the displaceable tongues in an embodiment according to the invention in a top view and a 3D view.
(8) FIGS. 8a-b show the bending of the protrusion of the tongue, during installation, according to embodiments of the invention.
(9) FIGS. 9a-d show installation with vertical folding or vertical locking according to one embodiment of the invention.
(10) FIGS. 10a-d show installation with snapping according to one embodiment of the invention.
(11) FIGS. 11a-d show an embodiment of installation with snapping facilitated by a flexible tongue and bending of a locking strip.
(12) FIGS. 12a-d show an embodiment of installation and disconnection of panels with angling.
(13) FIGS. 13a-b show an embodiment of an installation method.
(14) FIGS. 13c-e show embodiments with separate materials connected to the panel edge.
(15) FIGS. 14a-c show embodiments according to the invention.
(16) FIGS. 15a-b show embodiments according to the invention.
(17) FIGS. 16a-e show embodiments according to the third object of the invention.
(18) FIGS. 16f-g show embodiments of the tongue according to the invention.
(19) FIGS. 16h-i show embodiments of the invention.
(20) FIGS. 17a-c show embodiments of locking systems which could be applied in the fourth and fifth object of the invention.
(21) FIGS. 17d-e show embodiments of the invention.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
(22) As represented in FIGS. 5-17, the disclosure relates to a set of floor panels with a displaceable tongue, displaceable tongue for a floor panel, a locking system for floor panels and a method to install floor panels.
(23) A known art floor panel 1, 1′ provided with a mechanical locking system and a displaceable tongue is described with reference to FIGS. 1a-1d.
(24) FIG. 1a illustrates schematically a cross-section of a joint between a short side joint edge 4a of a panel 1 and an opposite short side joint edge 4b of a second panel 1′.
(25) The front faces of the panels are essentially positioned in a common horizontal plane HP, and the upper parts 21, 41 of the joint edges 4a, 4b abut against each other in a vertical plane VP. The mechanical locking system provides locking of the panels relative to each other in the vertical direction D1 as well as the horizontal direction D2.
(26) To provide joining of the two joint edges in the D1 and D2 directions, the edges of the floor panel have in a manner known per se a locking strip 6 with a locking element 8 in one joint edge, hereafter referred to as the “strip panel” which cooperates with a locking groove 14 in the other joint edge, hereafter referred to as the “fold panel”, and provides the horizontal locking.
(27) The known art mechanical locking system comprises a separate flexible tongue 30 fixed into a displacement groove 40 formed in one of the joint edges. The flexible tongue 30 has a groove portion P1, which is located in the displacement groove 40 and a projecting portion P2 projecting outside the displacement groove 40. The projecting portion P2 of the flexible tongue 30 in one of the joint edges cooperates with a tongue groove 20 formed in the other joint edge.
(28) The flexible tongue 30 has a protruding part P2 with a rounded outer part 31 and a sliding surface 32, which in this embodiment if formed like a bevel. It has upper 33 and lower 35 tongue displacement surfaces and an inner part 34.
(29) The displacement groove 40 has an upper 42 and a lower 46 opening, which in this embodiment are rounded, a bottom 44 and upper 43 and lower 45 groove displacement surfaces, which preferably are essentially parallel with the horizontal plane HP.
(30) The tongue groove 20 has a tongue-locking surface 22, which cooperates with the flexible tongue 30 and locks the joint edges in a vertical direction D1. The fold panel 1′ has a vertical locking surface 24, which is closer to the rear face 62 than the tongue groove 20. The vertical locking surface 24 cooperates with the strip 6 and locks the joint edges in another vertical direction. The fold panel has in this embodiment a sliding surface 23 which cooperated during locking with the sliding surface 32 of the tongue.
(31) FIG. 3a shows a cross section A-A of a panel according to FIG. 3b seen from above. The flexible tongue 30 has a length L along the joint edge, a width W parallel to the horizontal plane and perpendicular to the length L and a thickness T in the vertical direction D1. The sum of the largest groove portion P1 and the largest protruding part P2 is the total width TW. The flexible tongue has also in this embodiment a middle section MS and two edge sections ES adjacent to the middle section. The size of the protruding part P2 and the groove portion P1 varies in this embodiment along the length L and the tongue is spaced from the two corner sections 9a and 9b. The flexible tongue 30 has on one of the edge sections a friction connection 36 which could be shaped for instance as a local small vertical protrusion. This friction connection keeps the flexible tongue in the displacement groove 40 during installation, or during production, packaging and transport, if the flexible tongue is integrated with the floor panel at the factory.
(32) FIGS. 2a and 2b show the position of the flexible tongue 30 after the first displacement towards the bottom 44 of the displacement groove 40. The displacement is caused essentially by bending of the flexible tongue 30 in its length direction L parallel to the width W. This feature is essential for this known art.
(33) The fold panel could be disconnected with a needle shaped tool, which could be inserted from the corner section 9b into the tongue grove 20 and press the flexible tongue back into the displacement groove 40. The fold panel could then be angled up while the strip panel is still on the sub floor. Of course the panels could also be disconnected in the traditional way.
(34) FIGS. 4a and 4b show one embodiment of a vertical folding. A first panel 1″ in a first row is connected to a second 1 panel in a second row. The new panel 1′ is connected with its long side 5a to the long side 5b of the first panel with angling. This angling action also connects the short side 4b of the new pane with the short side 4a of the second panel. The fold panel 1′ is locked to the strip panel 1 with a combined vertical and turning motion along the vertical plane VP. The protruding part P2 has a rounded and or angled folding part P2′ which during folding cooperates with the sliding surface 23 of the folding panel 1′. The combined effect of a folding part P2′, and a sliding surface 32 of the tongue which during the folding cooperates with the sliding surface 23 of the fold panel 1′ facilitates the first displacement of the flexible tongue 30. An essential feature of this embodiment is the position of the projecting portion P2, which is spaced from the corner section 9a and 9b. The spacing is at least 10% of the length of the joint edge, in this case the visible short side 4a.
(35) FIGS. 5a-5c show an embodiment of the set of floor panels with a displaceable tongue according to the invention and a preferred installation method. In this embodiment the length of the tongue is of more than 90% of the width WS of front face of the panel, in other preferred embodiments the length of the tongue is preferably in the range from 75% to substantially the same as the width WS of front face. Preferably, the length of the tongue is about the total width of the panel minus the width of the locking system of the adjacent edges of the panel. A small bevel may be provided at the ends of the outer edge, but the straight part of the tongue at the outer edge has preferably a length substantially equal to the length of the tongue or desirably more than 90%. The new panel 1′ is in angled position with an upper part of the joint edge in contact with the first panel 1″ in the first row. The new panel 1′ is then displaced towards the second panel 1 until the edges are essentially in contact and a part of the flexible tongue 15 is pressed into the displacement groove 40 as can be seen in the FIG. 5b. The new panel 1′ is then folded down towards the second panel 1. Since the displacement of the new panel 1′ presses only an edge section of the flexible tongue 15 into the displacement groove 40, vertical folding will be possible to make with less resistance. Installation could be made with a displaceable tongue that has a straight outer edge. When panels with the known bow shaped tongue 30 (see FIG. 2-4) are installed the whole tongue has to be pressed into the displacement groove. When comparing the known bow shaped tongue with a tongue according to the invention less force is needed for a tongue with the same spring constant per length unit of the tongue. It is therefore possible, using the principles of the invention, to use a tongue with higher spring constant per length unit and higher spring back force, resulting in more reliable final position of the tongue. With this installation method, the beveled sliding surface of the fold panel is not necessary, or may be smaller, which is an advantage for thin panels. If the tongue is not long enough, the installation method above is not working and the beveled sliding surface of the fold panel is needed. FIG. 5c show that the tongue could be on the folding panel.
(36) A preferred production method according to the invention is injection moulding. With this production method a wide variety of complex three-dimensional shapes could be produced at low cost and the flexible tongues 15 may easily be connected to each other to form tongue blanks 50. A tongue could also be made of an extruded or machined plastic or metal section, which could be further shaped with for example punching to form a flexible tongue according to the invention. The drawback with extrusion, besides the additional productions steps, is that it is hard to reinforce the tongue, e.g. by fibres.
(37) As can be seen when comparing FIGS. 5 and 4, the angle between the new panel rand the second panel 1 is higher, for the panels with the tongue according to an embodiment of the invention, when the new panel initially contacts the end of the tongue 15 and begins to displace the tongue into the displacement groove 40. It is an advantage if the angle is higher, since a higher angle means a more comfortable working position in which it is easier to apply a higher force pushing the tongue into the displacement groove.
(38) Any type of polymer materials could be used such as PA (nylon), POM, PC, PP, PET or PE or similar having the properties described above in the different embodiments. These plastic materials could be when injection moulding is used be reinforced with for instance glass fibre, Kevlar fibre, carbon fibre or talk or chalk. A preferred material is glass fibre, preferably extra-long, reinforced PP or POM.
(39) FIGS. 6a-e show embodiments of the tongue 15 according to the invention. They are all configured to be inserted in a groove in a floor panel, in a similar way as described for the known art tongues and panels in reference to FIGS. 1-4 above. All methods to injection mould, insert and also the tool for disassembling described in WO2006/043893 and partly in the description and FIGS. 1-4 above are applicable to the invention.
(40) FIG. 6a shows an embodiment with a first long edge L1 and a second long edge L2. The first long edge has protrusions extending in a plane parallel to the topside 64 of the tongue 15 and with an angle relative the longitudinal direction of the tongue.
(41) FIGS. 6a-b show the embodiment, in top and in a side view, with a first long edge L1 and a second long edge L2. The first long edge has protrusions 61 extending in a plane parallel to the topside, an upper displacement surface 61, and rear side, a lower displacement surface, of the tongue and with an angle relative the longitudinal direction of the tongue. The protrusions are preferably bow shaped and, in a particular preferred embodiment, the tongue is provided with a recess 62 at each protrusion 61. The recess is preferably adapted to the size and shape of the protrusion.
(42) The protrusions are preferably provided with a friction connection 63, most preferably close to or at the tip of the protrusion, which could be shaped for instance as a local small vertical protrusion. This friction connection keeps the flexible tongue in the displacement groove 40 during installation, or during production, packaging and transport, if the displaceable tongue is integrated with the floor panel at the factory.
(43) FIG. 6d shows the tongue 15 in the cross section B-B in FIG. 6c and positioned in the displacement groove 40 of a panel 1. The upper and lower displacement surface of the tongue is configured to cooperate with an upper 43 and a lower 45 groove displacement surfaces. The panel comprises a locking strip 6 and a locking element 8 for horizontal locking. The panel 1 is configured to be connected to a second panel 1′ in a similar way as the known art panel 1′ in FIG. 1a-1d. The upper displacement surface (64) and/or the lower displacement surface (65) of the tongue is in one preferred embodiment provided with a beveled edge, presenting a sliding surface (32, 31) and an inclined locking surface (66), respectively. The inclined locking surface cooperates preferably with an inclined tongue-locking surface 22 in the tongue groove (20).
(44) In embodiments according to FIGS. 6d and 6e, the displacement groove (40) is formed in one piece with the core of the panel, but other alternatives are possible. The displacement groove may be formed in a separate material, for example HDF, which is connected to a wood core in a parquet floor. The displacement grove may be formed of U-shaped plastic or metal sections, which are connected to the panel with for example a snap connection, glue or friction. These alternatives could be used to reduce friction and to facilitate horizontal displacement of the tongue in the displacement grove. The displacement groove may also be treated with a friction reducing agent. These principles may also be applied to the tongue groove.
(45) FIG. 6e shows that the tongue 15 may also be inserted into the displacement groove 40 of a panel for locking in the horizontal plane. The tongue is displaced in the vertical plane during connection of the panels. These types of panels are connected by a movement in the horizontal plane—“horizontal snapping”.
(46) To facilitate the installation it is advantageous if the spring constant of the protruding part is as linear as possible. A linear spring constant results in a nice and smooth connection movement without suddenly or heavily increased displacement resistant. According to one embodiment, this is achieved by a bow shaped protrusion. FIG. 8b shows that a bow shaped protrusion results in an essentially constant moment arm, the force is during the whole course of connecting two panels at the tip of the protrusion, and an essentially linear spring constant. FIG. 8a shows that a straight protrusion results in that the moment arm is changed during the course; the force is spread out over a larger part of the length of the protrusion, resulting in an increased spring constant during the course. F is the displacement force and L is the displaced distance.
(47) The preferred recess at the protrusion has the advantage that the protrusion is not destroyed if too much force is applied or the tongue is displaced too far. The protrusion is pushed into the recess and a cracking of the protrusion is avoided.
(48) FIGS. 7a-b show two enlarged embodiments of a part of the tongue in a top view and in a 3D view. The figures show a casting gate 71 which is cut off before insertion into the displacement groove.
(49) It is preferred that the length of the protrusion PL is larger than the total width TW of the tongue. The total width is the width of the tongue W plus the distance from the tongue body to the tip of the protrusion perpendicular to the length direction of the tongue. In the most preferred embodiment, PL is larger than 2*TW. It is also preferred that the recess is wider near the tip of the protrusion than near the bottom of the recess; as shown I FIG. 7a.
(50) Preferably, the force to displace the tongue 1 mm is per 100 mm length of the tongue in the range of about 20 to about 30 N.
(51) Preferably the length of the protrusion PL is in the range of about 10 mm to about 20 mm, the width W of the tongue is in the range of about 3 mm to about 6 mm and the total width TW of the tongue is in the range of about 5 mm to about 11 mm. The length of the body part BP between two protrusions, i.e. the distance from the root of one protrusion to the tip of an adjacent protrusion, is in the range of about 3 mm to about 10 mm. As a non-limiting example, for a width of a floor panel of about 200 mm, including the width of the locking system at adjacent edges, with a tongue length of about 180 mm, having 9 protrusions the protrusion length is about 15 mm, the length of the body part BP is about 5 mm, the width of the tongue W is about 5 mm and the total width TW is about 8 mm.
(52) The tongues according to the embodiments of the invention are all possible to mould in one piece. It is further possible to cut the moulded tongue in shorter pieces which all have the same properties per length unit, provided that the number of protrusions is not too few. Another production method is extrusion combined with punching or cutting of the recess and the protrusions of the tongue.
(53) FIGS. 9a-9d show a locking system, which allow vertical folding and vertical locking according to the main principles of the invention. In order to facilitate locking, the locking system comprises a friction reducing agent (71, 71′, 71″) such as wax, oil or similar chemicals at the edge of folding panel 1′ and/or at the locking element 8 and/or at the locking grove 14. Preferably all flexible tongues shown in this application are provided with a friction reducing agent, e.g. wax or oil.
(54) FIGS. 10a-10d show that a locking system, which allows vertical folding, also could be designed to be locked with horizontal snapping. In this embodiment the snapping is mainly facilitated by the flexible tongue (15). The locking system could be designed to be locked with a substantial horizontal displacement or with a combination of horizontal and vertical displacement, as shown in FIGS. 10a-d. The outer parts of the tongue 15 and the edge of the folding panel 1 could be designed with bevels and/or rounded parts that facilitate snapping
(55) FIGS. 11a-11d show that the snapping could also be combined with a flexible strip (6) that during snapping is bended downwards towards the sub floor.
(56) FIGS. 12a-12d show that the locking system also could be designed to allow locking with angling. FIG. 12d shows that the locking system also could be unlocked with angling. Wax and other types of friction reducing agents could also be applied in the displacement groove, the tongue groove or in the locking system and especially on surfaces that during locking are in contact with the flexible tongue. Such friction reducing agent will improve the locking and unlocking functions in all locking systems, for example shown in FIGS. 2b, 13c-d, 14a-c, 15a-b and 17a-e where a part of a tongue is flexible. A locking system, which could be locked with vertical folding, vertical locking, angling and snapping, could have many different types of tongues, which are made of a separate material than the core of the panel, which tongues are connected to a panel edge and which tongues have at least one part that is flexible. Examples of embodiments of locking systems and separate tongues that allow such locking are shown in FIGS. 2b, 13c-d, 14a-c, 15a-b and 17a-e. All types of flexible tongues, which for example have snap tabs, are bended in length direction, have flexible protrusions inside or outside a groove etc. could be used. According to the invention a locking system with a separate tongue which has at least one flexible part is provided and this locking system has locking means which allow vertical and horizontal locking with vertical folding, vertical locking snapping with or without a flexible strip and with angling. It could also be unlocked by angling. Such a locking system will offer several advantages during installation of floor panels. Of course locking systems could be designed such that one or several of the above mentioned locking function could be prevented. For example a locking element, which has a locking surface essentially perpendicular to the horizontal plane, will prevent disassembly with angling up of the panel. Such a locking system will however have a high strength in the horizontal direction.
(57) Vertical folding is in most cases the most convenient installation method. However, FIGS. 13a and 13 b show an alternative installation method. The short sides of panels in a first row R1 are connected. The short sides of panels in a second row R2 are connected to each other by vertical locking or horizontal snapping where a part of a separate tongue, comprising a flexible part, is displaced during locking. Such a connecting method is extremely easy since the panels could be laid flat on the sub floor short edge against short edge and connected. They do not have to be angled or snapped together with a tapping block. The two adjacent rows R1 and R2 are then connected with angling.
(58) The method comprises installation of floor panels comprising short edges with a mechanical locking system for locking the adjacent short edges vertically with a separate tongue comprising a flexible part and horizontally with a locking strip comprising a locking element and long sides with a mechanical locking system comprising a tongue, a groove a locking strip and a locking groove that allows vertical and horizontal locking by angling
(59) a) Installing a second row R2 of panels by connecting the short sides of the panels with vertical locking or horizontal snapping whereby the flexible part of the tongue is displaced
(60) b) Connecting the second row R2 to an installed and adjacent row R2 by angling.
(61) FIGS. 13c-13e show that separate materials 72-73 could be used to improve strength and locking functions. Such separate materials that could be connected as an edge portion in a for example a laminate or wood floor panel and they could preferably comprise hard wood, plywood, plastic materials, HDF, MDF and similar. Separate materials could be attached to one or both edges. They could form a part of the displacement groove, as shown in FIG. 13c, a part of the tongue groove 20, as shown in FIG. 13d or even at least a part of the locking strip 6 and the locking groove 14 as shown in FIG. 13e. Separate materials could be used in all locking systems with separate and partly flexible tongues. These principles could be used for example in locking systems shown in FIGS. 17a-17e.
(62) FIGS. 14a and 14b show that the protrusions 61 could be located inside or outside the displacement groove 40. The flexible protrusions, which are located outside the displacement groove, could be designed to cooperate with the tongue groove and to lock the panels vertically.
(63) FIG. 15a shows an embodiment of the flexible tongue 15 with protrusions 61 partly outside the displacement groove and with a bow shaped inner part.
(64) FIG. 14c shows that one short edge portion (E1) of the flexible tongue (15) which is located in the same direction as the direction as the protrusions, will bend out (provided that the friction connection do not prevent such bending) if a force F is pressed against the tongue when it is in the displacement groove with the protrusions inside the groove. Therefore it is preferred that in this embodiment, protrusions should be directed towards the part of the panel where the folding starts, as shown in FIG. 14a. Such an embodiment offers the advantage that the flexible tongue will not snap out during the final part of the folding. It is preferred that the flexible tongue has at least one rounded or beveled end portion (70). Such a portion could be integrated in a moulded tongue. It could also be for example a punched or cut part in a tongue, which is extruded. In this embodiment there are protrusions 61a and 61b at the edge portions of the tongue and these extrusions extend in different directions away from each other. The tongue has also two short edge portions E1 and E1 which are formed such that they do not extend outside the displacement grove as much as the middle part of the tongue. Such an embodiment will facilitate installation. The shape of the protrusions and the short edge portions could be used separately or in combination.
(65) FIG. 15b shows an embodiment with flexible tongues 15, 15′ on two opposite edges of the same panel. This is useful in advanced installations. All embodiments of separate tongues shown in this application could be used.
(66) FIGS. 16a-16e show embodiments of a flexible tongue 15 with protrusions. FIG. 16a shows protrusions 61 with beveled or rounder tips (71). FIG. 16b shows the protrusions in a compressed position when they are pressed into the displacement groove 40. FIG. 16c shows round shapes 72 at the outer part of the protrusions, which facilitates installations with vertical folding from both long edges.
(67) FIGS. 16d and 16e show embodiments with double protrusions 16, 16′ inside and outside the displacement groove 40. All embodiments could be combined. For example a tongue with double protrusions as in FIGS. 16d and 16 e could have rounder outer parts 72 as in FIG. 16c.
(68) FIGS. 16h and 16a-b show that the flexible tongue 15 could have a body 15a which is slightly thicker than the part of the part 61a of the protrusion 61 which is displaceable in the displacement groove 40 during locking. The play between the displacement grove and the protrusion reduces the friction and facilitates a reliable displacement of the protrusion 61. It is preferred that protrusions and flexible parts are such that the parts of the tongue which lock in the tongue groove exert a pressure force in locked position. An example is a tongue, which comprise flexible parts, which after 100 hours of compression, corresponding to the compression during vertical folding, could spring back to a position, which is at least 90% of their initial position.
(69) FIGS. 16f and 16g show embodiments of the tongue, which are symmetric in a vertical plane perpendicular to the edge of the floor panel. These tongues have the same properties for both folding directions. The tongue in FIG. 16g with protrusions extending outwards at both ends of the tongue also has the advantage of support at the outer most edge of the tongue. In another preferred embodiment of a tongue with protrusions only in one direction, the tongue is symmetric in a horizontal plane, which gives the advantage that it is possible to turn the tongue upside down, resulting in the same properties for both folding directions.
(70) A locking surface of a locking element 8 at a locking strip 6 could be made with different angles, bevels and radius. The locking surface of the locking element 8 may e.g. extend inwardly towards the upper edge of the panel, as shown in FIG. 16i. The vertical locking could in such an embodiment consist of a flexible tongue 15 and a locking element 8 on a locking strip 6.
(71) FIG. 17a shows a flexible tongue 15 with flexible tab 75 extending upwards. The flexible tongue is connected to the folding panel 1.
(72) FIG. 17b shows a flexible tongue 15 with flexible tab 75 extending downwards. The flexible tongue is connected to the edge, which has a locking strip 6 extending from the edge. This embodiment is an improvement of the locking system shown in FIG. 17a since the flexible tab is not displaced by a sharp panel edge. The folding panel could be formed with a sliding surface 23, which facilitates the displacement of the snap tab 75. The snap tab could be designed with a pre-tension, which presses the folding panel downwards in locked position. The tongue with the flexible tab 75 could be combined with a bow shaped form or protrusions according to the main principles of the invention.
(73) FIG. 17c shows that a flexible tab 75 could be located inside a displacement groove. It could be directed upwards or downwards and a separate tongue could have flexible tabs inside and/or outside a displacement groove.
(74) FIG. 17d shows an embodiment with two displaceable tongues 15, 15′ over and under each other. FIG. 17e shows that the flexible tongue could be locked against a part of the locking strip 6. All tongues shown in this application could be used in such locking systems.
(75) A flexible tongue with protrusion could be used to lock very thin floor panels for example about 6 mm and even thinner. Even with a vertical thickness of a flexible tongue of about 1 mm a strong vertical locking could be obtained. Protrusions could be made extremely small. They could for example extent only about 1 mm or even less into the tongue groove and there could be more than 1 protrusion per 10 mm of the tongue length.
